Feasibility and accuracy of a novel automated three-dimensional ultrasonographic analysis system for abdominal aortic aneurysm: comparison with two-dimensional ultrasonography and computed tomography

Abstract

Background: Accurate measurement of the maximum aortic diameter (Dmax) is crucial for patients with abdominal aortic aneurysm (AAA). Aortic computed tomography (CT) provides accurate Dmax values by threedimensional (3-D) reconstruction but may cause nephrotoxicity because of contrast use and radiation hazard. We aimed to evaluate the accuracy of a novel semi-automated 3-D ultrasonography (3-D US) system compared with that of CT as a reference. Methods: Patients with AAA (n = 59) or individuals with normal aorta (n = 18) were prospectively recruited in an outpatient setting. Two-dimensional ultrasonography (2-D US) and 3-D US images were acquired with a single-sweep volumetric transducer. The analysis was performed offline with a software. Dmax and the vessel area of the Dmax slice were measured with 2-D US, 3-D US, and CT. The lumen and thrombus areas of the Dmax slice were also measured in 40 patients with intraluminal thrombus. Vessel and thrombus volumes were measured using 3-D US and CT. Results: The Dmax values from 3-D US demonstrated better agreement (R 2 = 0.984) with the CT values than with the 2-D US values (R 2 = 0.938). Overall, 2-D US underestimated Dmax compared with 3-D US (32.3 ± 12.1 mm vs. 35.1 ± 12.0 mm). The Bland-Altman analysis of the 3-D US values, revealed better agreement with the CT values (2 standard deviations [SD], 2.9 mm) than with the 2-D US values (2 SD, 5.4 mm). The vessel, lumen, and thrombus areas all demonstrated better agreement with CT than with 2-D US (R 2 = 0.986 vs. 0.960 for the vessel, R 2 = 0.891 vs. 0.837 for the lumen, and R 2 = 0.977 vs. 0.872 for the thrombus). The thrombus volume assessed with 3-D US showed good correlation with the CT value (R 2 = 0.981 and 2 SD in the Bland-Altman analysis: 13.6 cm 3).

Three-dimensional ultrasound improves identification of patients with abdominal aortic aneurysms reaching the threshold for repair

“…By implementing 3D-US in the decision process, a five-fold decrease in the risk of underestimating the AAA size was observed. Previous studies comparing 3D-US and 2D-US diameter assessment with CTA have already shown superior agreement between 3D-US and CTA in native AAA, 13,18,22 and the 3Dderived dual-plane technique implemented as standard US-modality for AAA surveillance in our J o u r n a l P r e -p r o o f clinic, has shown to minimise the operator variability and improve agreement with CTA 13 . Nevertheless, other centers, using conventional 2D-US, might experience an even greater difference between US and CTA diameter, than evident in the current study, which furtherly advocates a future shift from 2D to 3D imaging.…”

Correlation of four-dimensional ultrasound strain analysis with computed tomography angiography wall stress simulations in abdominal aortic aneurysms

“…14 , 15 Segmentation and analysis of CTA, as well as registration with segmentation of 4D-US imaging, were performed by three independent investigators. We have not proven the interobserver variability of single examinations, 16 reliability of the segmentation process, and value of the averaged models for 4D-US, 14 , 15 , 17 as well as the reliability of the segmentation of the geometry and stress analysis for CTA 18 once again, because these processes have already been published and classified as reliable. However, we registered the conformity of AAA geometry in the 4D-US and in the gold standard CTA as the absolute prerequisite for the comparative analysis of wall strain and wall stress.…”

Using averaged models from 4D ultrasound strain imaging allows to significantly differentiate local wall strains in calcified regions of abdominal aortic aneurysms

“…CT-A is considered a gold standard for geometry reconstructions mainly because it is a suitable tool for imaging the entire aneurysm and accurately measuring AAA size with high reproducibility (Cho et al. 2020 ) and has been established in the past as a suitable means for measuring and detecting AAA growth (diameter and volume) with high accuracy and reproducibility (Bargellini et al. 2005 ; Kauffmann et al.…”

“…Also 3D ultrasound could be found to be a suitable method to determine maximal diameter, vessel area as well as vessel and thrombus volume with excellent agreement compared to CT imaging (Cho et al. 2020 ). The median Hausdorff Distance found here between the US and CT-A geometries of 5.1 [4.5, 6.1] mm is in good agreement with 4.6 [4.0, 5.9] mm from van Disseldorp et al.…”